"Ideally, would he be a politician who's up for public relations and razzmatazz alongside his serious side and his devotion to getting policies right? Well, ideally, yes.

"But in a choice between somebody who's serious and somebody who's shallow but looks good on TV, I think the British public will go for the former."

Asked about Mandelson's comments, Brown said: "I think people should just wait."

Brown may have been referring to his speech at next week's Labour's conference, which will be one of the most high profile he delivers before the general election.

In his interview Mandelson also saidthat Labour needed to "get our campaigning act together better than we have done in the past year".

As the underdog, the party must "bark back and bark loudly", he added.

Asked about Mandelson's remark about Labour being the underdog, Brown said: "We are fighters because we believe what we are doing. I come from a family that thinks you can get on by hard work, by effort, by putting your case strongly and we will not give up putting the case that we have got to put to the British public."

Mandelson also admitted that "a handful" of MPs would "never be reconciled" with Brown's leadership.

Yesterday the prime minister was forced to brush off Clarke's acerbic comments and speculation that he may quit on supposed health grounds.

He told BBC Radio 5 Live: "I am healthy and I am very fit. I run a lot to keep fit and I will continue to keep fit.

"I keep going. I have got a job to do. I have got work to do. We have got to meet this challenge."

Alistair Darling, the chancellor, publicly defended his leadership, telling the Spectator: "I've really got no time for people who say: 'If only there was someone else, it'd be all right.' That's bollocks, you know."